Electrical system fob aircraft



Jul 15 1924. 1,501,508

L. m-wooLsoN IFZLEGTRICAL SYSTEM FOR AIRCRAFT Filed Nov. 14. 1917 2Sheets-Sheet 1 all] INVENTOR A .w HJ

TORNEYs July; .15 1924 L. M. WOOL-SON ELECTRICAL SYSTEM FOR AIRCRAFTFiled Nov. 14. 1917 2 Sheets-Shem. 2

- IN ENTOR LAO-.4 xlum V MJREWI we d s! 1 9 STATES BATENT LION L Q 'SQDAYT 03in, ASSIGNQR, B final-m 1'0 AY ON; ENG N RING LABORATORIES oonrm,Aconrona'rronon 031g;

ELECTRICAL SYSTEM FOR AIRCRAFT.

Application filed l lovcrnber 14, 1917. Serial No. 201,974.

the blocks of the V at a relatively small To all whom it my concern:

Be it known that I, LIONEL M. Woonson, a citizen of the United States,and a resident of the cit Y of Dayton, countyof Montgbmery, and gtate ofOhio, have invented an Improvement in Electrical Systems for Aircraft,of which the following is afspeci fication. I This. invention relates toelectrical systems for internal combustion en ines, and with regard toits more specific eatures to electrical' systems for eng nes designedfor air lane 'propulsion'. ne of'the objects thereof is to provide anignition system involving apparatus of simple, light and ruggedconstruction, specially suitable for modern airplane engines of certaintypes."

Another object is to provide in apparatus of the above type an ignitionsystem which will function efliciently under all conditions of operationand which is unlikely to break down.

Qtherobjects will be in part obvious and in part pointed outhereinafter.

The invention accordingly consists in the features of construction,combinations of elements and arrangement of parts which will beexemplified. in the construction hereinafter set forth, and t lge scopeof the application of which will e indicated in the following claims.

In the accompanying drawing wherein is shown one of various 'pomibleembodiments of the several features of-this invention, Fig. 1 is an endview of the engine showing the parts .of the ignition system in apreferred relation.

Fig. 2 is a diagrammatic view of the ignition circuits thereof and Fig.3 is a detail view of the interrupter cams showing their preferredangular relation.

Similar reference characters refer to similar parts throughout thedifferent views.

of the drawings.

In the specification and claims I intend the -term V-t 0 engine to applyto any engine in w ich the axes of some cylinders are at an angle tothose of others.

As conductive to an understanding of some of the features of thisinvention, it may be noted that in airplanes in which, as is well known,the V-type of engine is particularly advantageous, greater efiioiency ofthe vehicle is secured y arranging :in the width of the engine so thatanarrower fuselage may be employed with consequent reduction of theresistance of; the atmosphere a ainst pro ress of the vehicle. I This ateration o the conventional form of V*-type engine makes-it desirable tointroduce certain chan' s in the conven tlonal ignition system wit aview to scouring a high 'efliciency of action, and one of theobjectsofthe invention as abovenoted is to bring about such eflici'encReferring now to 'Fi 1 of the drawings, there is shown an eiglt'cylinderengine 1 of the V.-type having an an 1e between its cylinderblocks 2 and 3 of instead of'the angle" of 90 degrees, usual in eightcylinder engines of the V-typ'e. The term block is used in thespecification and claims, without regard to the manner in which thecylinders are cast, the term being used generically as meaning group of;cylinders v regardless of. construction. It is obvious that after firinof a c linder in the left hand block of a our cyc e eight 0 linder enineof the V-t' with its bloc s disposed as in Fig. 1, t e explosion inthe next cylinder in order of firing of the right block, will take laceafter a' 45' degree'turn of the cranks aft. Thereupon a turn of 135degrees of the crankshaft will be necessary before. the next ex losionwill take place in acylinder on the. eft hand block, and thusexplosionsexplosions, to define the angle betwcen' crankshaft positionsfor successive explosions.

A preferred location of the ignition apparatus for the engineis'indicated in Fig.

ut 45 degrees 1. Mounted substantially centrally between blocks 2 and 3,and near the apex of the V is'a current enerator 4, driven preferably.at twice .cran -shaft speed, and having a .special construction of timerT, preferably splined on its shaft, as shown at 55, and driven thereby.For reliability of action,

' two i'.substantially independent ignition systerns are preferablyprovided, both deriving their, current from the generator 4. Theseignition systems are substantially dupli-' cates, an induction coil 5being preferably mounted on one cylinder block, and a similar inductioncoil 6 on the other, there being spark plug 16 is connected to contact60 on the ad acent distributer and spark plug 15 of the same cylinder isconnected to contact 61 bff the distributer associated with the othercylinder block. Similarly spark plug 16" on a cylinder of the right handblock is connected with contact 63 of the adjacent distributer, andspark plug 15' of the same cylinder is connected to contact 64.- of thedistributer 7 associated with the left hand block. In this manner-thetwo spark plugs of each cylinder are connected one with the thedistributer on the same block and the other with the distributer on theother block. Thelispark plugs of each-cylinder are thus connected tobecaused to fire simultaneously, one being energized by way of distributr'Zjand the other by way of distributer 8. Theconnections from eachdistributer are of course in the same order as the cylinders aredesigned to fire. The. engine as is noted is preferably provided withoverhead camshafts' 17 to which the distributers are at; tached and bywhich they are driven.

" It may here be noted that the duplicateignition systems not onlyfurnish protection in case one systemshould break down-in normaloperation, but lhe induction coils and distributers are so spaced thatin the case of airplanes used in warfare a small; projectile is unlikelyto simultaneous- 1y cripple both systems. An auxiliary ignition systemused for starting is shown mounted at 50. The detailed construction of.all. of the ignition systems will be more fully described below.

Referring now to Fig. 2, there is shown preferably a generator. 1-having main rushes 56 and 57 in neutral position, an auxiliary brush 58and the field coil 59 connected between brushes 5? and 58, which ar-*rangement will reduce substantially constant current wit varyingspeeds. It is to 12. The two cams are substantia be understood thatother regulating means for this result may be employed to advantage.,One of the generator terminals is preferably grounded or connected to ametallic structure of the airplane. The generator leads current to theprimary 9 of an induction coil 5 and from there through interruptercontacts 11 back to ground or a metallic structure of the machine, theconis led to arm 35 of a distributer 7 of special construction whichwill be described in greater detail below.

As described above, it is preferable to provide two separate ignitioncircuits, the second circuit being substantially identical with thefirst just described, the induction coil 6 having a primary 10 and asecondary 39, the second interru ter being shown at 12 and being bridgedy condenser 14 and the second distributer being shown at 8.' It is, ofcourse, to be understood that the second 'ignition circuit ma bedispensed with, but

there are specially eneficial features of operation resulting from itsuse.

For reliability of action and in accordance with the peculiarconstruction of engine above described, the ignition system ispreferably dtsigned to produce its ignition sparks at unequal intervalscorresponding to crankshaft rotations of 45 degrees and 135 degreesalternately. This is brought'about by employing the special constructionof cams shown at 19 and 20. These cams are shown in Fig. 3, the cam 19operating contacts 11 and the cam 20 operating contacts ly identical andoperate in synchronism, so that the description below Wlll apply toeither. As shown, the operating irregularity 21 which opens theinterrupter 11 to produce a spark is succeeded after a 90 degree turn ofthe cam by operating irregularity 23, the contacts having automaticallyclosed by thesaction of spring 52 immediately after irregularity 21passes roller 22. After operating irregularity 23 is passed, the interruter contacts are maintained opened until axls 25 reaches roller 22 whenthey again close and again reopen when irregularity 21 reaches roller22. It is thus seen that the opening of the be at alternate angulardistances of 22% de-,

' grees and 67% degrees. Since the distributers are operated .by thecamshafts and at one-half crankshaft speed, the angles of 2% and-67%degrees correspond respectivel to angles of 45 degrees and 135 degrees 0the crankshaft. It is thus seen that the ignition system disclosed willproduce sparks at a=l ternate intervals of 45 degrees and 135 degrees ofcrankshaft position.

It is to be noted that the angular. distance between the closure ofthecam at 25 and the irregularity 21 is the same as that between theclosure of the interrupter at 26 and the irregularity 23. By thisarrangement, a uniform amount oftime is allowed for building up of themagnetic flux for the primary coil regardless whether a 45 degreeinterval of crankshaft rotation or a 135 degree interval precedesfiring. The camin its operation it is seen does not permit a reclosureof the interrupters immediately after irregularity 23 has caused theopening, but it maintains the contacts in open position until point 25reaches the roller. The cams as is seen are diametrically symmetrical inform. If the interrupter contacts were allowed to close auniforminterval aftertheir openingit is clear that a hotter spark wouldresult after a 135 degree interval than after a 45 de es intervalso'that the firing of the cylin ers of block 3 would be less efiicientthan that of block 2 bringing about a very undesirable irregularity ofaction of the engine.

For starting the engine, since the generator 4 does not then operate, aseparate source of ignition current for starting should be provided aridthe spark should preferably be retarded. For this reason, an auxiliaryignition system is provided for-the starting operation. This system ispreferably of the .vibrator type to produce a shower of sparksparticularly effective during starting.

Referring to Fig. 1 there is shown a dry or other light battery 27 whichis grounded or connected to a metallic structure of the airplane whenswitch 32 is placed on contact S, and will when contacts are closed leadcurrent through primary coil 28, contacts 65 and back to ground. Wheninterrupter contacts 65 are closed, this induction 0011 which. has theusual vibrator contacts bridged by condenser 52 will open the batterycircuit overcoming the resistance of the contacts repeat this cycle,vibrating with great rapidity in the well known manner. It is thus seenthat while contacts165 are closed, a succession of impulses is inducedin the secondary for producing a shower of ignition sparks as more fullydescribed below.

Cam 18 ,whichoperates contacts 65 of the auxiliary ignition system may,as shown, .be substantially identical in shape and size with cams 19 and20, but, unlikethe latter, the operating irregularities of: cam: 18, forreasons just outlined, are the depressions 40 and 41 which bring aboutclosure instead of opening of contacts 35. As shown, these operatlngirregularities are retarded 90 degrees behind the operatingirregularitiesof cams 19 and '20. The cams 19 and 20 are fixed on thegenerator shaft with a 90 degree lead with respect'to the starting cam,and the cams turning at twice crankshaft speed, cams 19 and'20 willproduce a spark advanced by 45 degrees with respect to that produced bystarting cam 18.

The secondary'29 of the induction coil leads to a conducting ring 30 ondistributer 8 and is by means of this ring 30 brought into electricalconnection with a distributer arm 31 maintained preferablynon-adjustably 22% degrees behind the main distributer arm 36 abovedescribed. A conducting strip 31' on arm 31 connects ring 30successlvely with the distributer contacts. The conductin portion 36 ofarm 36 is preferably-de ected as shown at 53 to be out of conductive:relation with ring 30. Either conducting strip 31 or 36 or both of themare preferably embedded in the insulating material of the correspondingarm to prevent jumping of spark from one strip to the other. Since thedistributer rotates at onehalf crankshaft s eed it is seen that the anlar distance 0 22% degrees between distri ute'r arms corresponds to anangle of 45 degrees of flywheel position. If the arms 35 and 36 beproperly synchronized with contacts 11 and 12, that. is if thesecontacts are arranged to open the instant the arms each reach adistributer contact, then the ignition circuit for starting will withoutfurther adjustment produce a spark retarded 45 degrees behind the normaloperating spark By this arrangement, if the normal operatin spark bemade to occur at a 45 degree a Vance, the spark for starting will occurat top dead center of each piston. If as is the case in some types ofengine, a'spark advance of less than 45 dees is desired, such adjustmentis readily effected. 'The ignition spark for starting because of itsnon-adjustable relation of 45 degrees behind the normal operatinignition spark will in such case occur ehind to center, which results inefliclent operation. In accordance with the characteris-- cause rapidalternate opening and closure of.

'need be made in the operation of the machine, the advance .having oncebeen properly set. The operating ignition circuit having been properlytimed, the auxiliary ignition apparatus for starting will withoutfurther adjustment operate efliciently 45 degrees behind the mainignition apparatus as above indicated.

The switch 32 has two positions S and O. 1

As described above, when in position S the ignition circuit for startingis closed. When laced in intermediate position indicatedby ,this circuitis open, and when 111 os1- tion 0, the main brushes 56 and 57 o thegenerator are short-cireuited substantially as in the case of thestoppin switch of a high-tension magneto, rendering this generatorincapable of producing ignition current. When switch 32 is in anyposition other thanposition O, the generator may be operative. A coilspring 66 is preferably located to be compressed when the switch is inposition S so that the ignition circuit for starting is closed only whenmaintained in this position by the hand of the operator.

The construction of the device having been above set forth, theoperation is substantially as follows: The airplanev driver holds switch32 in position S, and the engine is thereupon cranked either by hand orby electric or other power. As soon as an irregularity 40 or 41 on cam18 brin about a closure of contacts 'the battery 27 will lead currentthrough the primary 28 and the primary circuit. The secondary 29 will,therefore, in well-known manner, lead 1mpulses of current to ring 30 andfrom there throu h arm 31 in succession to the various c lin ers as arm31 is turned by the camshaft. In this manner a shower of sparks will becaused to take place in each cylinder until the engine runs under itsown power. IV hen this occurs switch 32 may be allowed to open to placethe auxiliary ignition circuit out of action and this switch is thenplaced in position R. The generator 4 will now be operating withsuflicient speed to generate ignition current, and when thesimultaneously operating interrupter contacts 11 and 12 are closed, thetwo main ignition circuits will be closed the one from ground, or ametallic structure of the 'machine, through the enerator, primary coil 9contacts 11 and back to ground, and the other through primary coil 10,interrupter 12 and back to ground. As soon as the irregularities 21 or23 on the cams 19 and 20 cause the interrupters to open, the arms 35 and36 being then in conductive relation each with a distribut-er contact, acurrent impulse will be sent by the secondaries of the induction coils 5and 6 res ctively to the two spark plugs of that cylinder correspondingto the position of the arms. As is readily understood this operationwill be repeated at alternate intervals of a 45 degree and 135 degreeturn of the crank-shaft resulting in proper ignition. When it is desiredto stop the operation of the ignition system, the switch 32 is moved toposition 0 to short-circuit the generator by grounding brush 57. In viewof the shape of the cams the time for building up flux for the primaryas above described is the same for all cylinders.

If'switch 32 is allowed to remain closed after starting, it will merelyproduce a harmless ignition spark 45 degrees later than the generatorspark and nothing objectionable will occur beyond unnecessary depletionof dry battery 27.

As is seen the ignition enerator is not supplemented by a stora e atteryfor running, but alone supplies t e generative force for the ignitionspark. No storage battery holding down the voltage of the generator, thebeneficial feature of operation results that as the engine speeds up,the generator produces current at a higher voltage in order to retainthe constancy of the am erage, thus obviating the loss in hotness ospark which would result from the lessened time allowed ,fior buildingup of magnetic flux within the induction c011.

Having reference to distributer 8 shown in the drawing, it is to benoted that by employing the angle of 2% degrees between distributer arms31 and 36 and by using the conventional length of arms there will be adistance of not less than inch between the parts of the distributor armcontacts in closest proximity to each other. This distance being thesame as that between the distributer contacts which are spaced by 2%degrees, it is seen that jum ing of sparks from arm 31 to 36, or fromeither arm to a contact other than that designed to be next in order iseffectively avoided. This correct operation occurs although the diameterof the'distributer is no greater than'in the usualcommercial single armtype.

If the conventional type of two pole magneto were employed to supply theignition current it is c ear that the same would have to be operated atfour times engine speed in order to produce sparks at a 45 degreeinterval of crankshaft position with the difiiculties resulting fromsuch high speed of operation apparent to those skilled in the art.

Although the above description'has been applied specifically to aV-typeengine havto be noted that this invention is applicable to engineshaving any number of cylinders compatible with the V-typeconstructionand that any desired angle may be maintained between the cylinderblocks. However, it is to be noted that there are certain speciallybeneficial characteristics inherent in the spe. cific construction shownand described.

Itwill thus be seen that there is herein described apparatus in whichthe several features of this invention are embodied, and

.whichapparatus in its action attains the various objects of theinvention and is well suited to meet the requirements of practical use.

As many changes could be made in the above construction, and manyapparently widely difi'ere'nt embodiments ofthis invention could be madewithoutdeparting from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. In an eight cylinder V-type internal combustion engine, incombination, two cylinder-blocks arranged at an angle to each other ofsubstantially one-half the average angle between explosions, and anignition system including an induction coil, and a cam for affecting,said induction coil to build up uniform magnetic flux thereinatintervals alternating in the ratio, of oneto.

three.

2. In a V-type internal combustion engine, in combination, twocylinder-blocks arranged at an angle to each other of substantiallyone-half the average angle between explosions, a direct current i itionsystem including an operating cam aving its operating irregularitiesspacedfrom each other at alternate'angular intervals having the ratio ofone to three, and a complementary irregularity preceding each operatingirregularity, said complementary irregularities bein of uniform length.

3. In an eight-cylinder V-type internal combustion engine, incombination, two cylinder blocks arranged at an angle to each other ofsubstantially 45 degrees, and an ignition system including aninterrupter cam driven at twice crankshaft speed and having two circuitinterruptin eccentricities spaced at substantially 90 egrees.

4. In an eight cylinder V-type internal combustion engine, incombination, two cylinder-blocks arranged at an angle of 45 de grees toeach other, an ignition system includin an interruptercam, driven attwice cranks aft speed, said cam having two operating irregularities 90degrees apart and said cam being diametrically symmetrical.

5. In an eight-cylinder V-type internal combustion engine, incombination, two cylinders arranged at an angle of substantially 45 derees to each other, an ignition system inclu ing a timer, rotatableattwice crankshaft speed, a distributer rotatable at onehalf crankshaftspeed, there being two operating irregularities on the cam of saidtimer, 90'degrees apart, and the distributer contacts being spacedalternately at 22% degrees and 67% degrees.

'6. In an ignition system for internal combustion engines, incombination, a distributer having a center contact, and a concentricconducting ring contact, an electric generator driven from said engineelectrically connected with one of said contacts and a chemical sourceof ignition connected with the other contact, a distributer armconnected with the same contact as said generator, and a seconddistributer arm retarded by a definite angle behind said firstdistributer arm and electrically connected with the other said contact.

7. In a V-type airplane engine, in com-. bination, two cylinder-blocksarranged at an angle to each other of substantially one-half the averageangle between explosions, an ignition system therefor, including asource of ignition current for starting, an ignition generator drivenfrom said engine for running, a distributer having the angles betweensuccessive contacts thereof alternating in magnitude in the ratio of oneto three, said distributer having two arms spaced from each. other b anangle-substantially equal to the sma ler angle between said contacts,the more advanced of said arms being connected to said generator, andthe more retarded to said starting source.

.8. In an eight-cylinder V-type internal combustion engine, incombination, two 0 1- inder-blocks arranged at an angle of 45 egrees toeach other, an ignition system thereor inelugling' a source of ignitioncurrent for starti g, an ignition generator driven from said engine forsupplying ignition current during running operation, a distributerhaving an arm in a position corresponding substantially to dea centerposition an connected with said starting source, a sec ond arm locatedfor substantially 45 degreesadvance, and connected with said generator,said arms being non-adjustable with respect to each other, whereby theangular distance between said arms is equal to the smaller of theangular distances between distributer contacts.

9. In a V-type internal combustion engine, in combination, twocylinder-blocks arranged at an angle to each other of substantiallyone-half the average angle between explosions, an ignition system havingtwo substantiall identical timers, the interrupter; cams t ereofhavingtheir operating irregularities spaced from each other by ang esalternating in magnltude 1n the ratio of one to three, one 'of saidtimers bemg angularly advanced with respect to the other.

10." In an eight cylinder V-type internal combustion engine, incombination, two cylinders arranged at an angle of substant ally45'degrees to each other, an lgnition system including a currentgenerator driven at .twice engine speed, two timers mounted on the axisof said generator, each timer cam 1 having two operating irregularitiessubst'antiall 90 degrees apart, and being diametrica y symmetrical, themore retarded Tcam being employed during starting,

' and the more advanced during running operation.

.11. In a V-type internal combustion eng ine, in combination, twocylinder-blocks arranged at an an le to each other of substantiallyone-ha] the average angle between explosions, an ignition systemincludingtwo timer cams each having itsoperating irregularities spacedfrom each other at angles alternating in magnitude in the ratio-of threeto one, a distributer having its contacts spaced from each other at an:

. gles alternating in magnitude in the ratio of three to one, said timercams being an larly spaced from each other, and said istfibuter havingtwo rotatable contacts spaced at an angle corresponding to that betweenthe cams.

' 12.;In an eightcylinder V-type internal combustion engine, 1ncombination, two,

cylinder-blocks arranged at an angle to each other of substantiallydegrees, an igmtion system including two substantially identical andcoaxial timer cams rotating at twice crankshaft speed, each cam havingtwofoperating irregularities spaced at an angle of 90 de ees and thecams being angu'larly space with respect to each other for operation 90de ees a art, a distributer rotatable at one-ha 15 cm .distributer arm,and a second induction,

coil, having its primary interrupted by the more .retar ed cam, and itssecondary lead- .ingto the more retarded distributer arm.

13. In an eight cylinder V-type internal combustion engine, incombination, two cylinder-blocks arranged at an angle to each other ofsubstantially 45 degrees, an ignition system, including a substantiallyconstant current generator located between woman the blocks, and drivenat twice crankshaft speed, two substantially identical timer camsrotatable with the shaft of said generator, each of said cams havin twooperating irregularities spaced at 90 egrees from eac other, said camsbeing diametrically symmetrical, and displaced with respect to eachother for operation 90 degrees apart, a distributer mounted on acamshaft of the engine, said distributer having eight contactsalternately spaced fromeach other by 2% de rees and 675; degrees, andtwo distri uter arms spaced by 2% degrees, the more advanced cam and themore advanced arm being synchronized.

14. In an eight cylinder V-type internal combustion engine, incombination, two cylinder-blocks arranged at an angle to each other ofsubstantially 45 degrees, an ignition system, including asubstantiallyconstant current generator located between the blocks and driven attwice crankshaft speed, three substantially identical timer camsrotatable with the shaft of said generator, each of said cams having twooperating irregularities spaced at 9(Ldegrees from each other, said camsbeing diametrically symmetrical, one of said cams being angularlyretarded for operation 90 degrees behind the other two, twosubstantially identical distributers, one driven from each cam shaft,said distributers having eightcontacts alternately spaced from eachotherby 2% degrees and 6 degrees, one of said distributers having two armsspaced by 2% degrees, the more advanced cam being synchronized with themore advanced of the latter two arms, and the other cams beingsynchronized one with each.of said other arms.

15. In an ignition system for internal combustion engines, incombinatitn, a plurality of ignition circuits and a substantiallyconstant current generator connected with each of said ignitioncircuits, said circuits consuming the entire .output of said generatoras it 1s generated.

16. In a V-type airplane engine, in combination two cylinder blocksarranged at an angle to each other of less than the average an lebetween explosions, an ignition system or starting including a primarybattery as a source of energy, an lgnition system for running operationincluding an electromagnetic source of energy, said first ignitionsystem havin means for deriving a shower of sparks uring startin saidprimary battery which shower s all be of uniform duration for thecylinders of both blocks, and means for allowing in said electromagneticsystem a period for building up of the magnetic flux preparatory to eachs ark, which has the same value for the cy index-s of both blocks.

17. In an ignition system for internal combustion engines, incombination a plu- 3% from rality of ignition circuits including 1 tioncoil apparatus, a substantia y constant current generator connectedacross said I said induction coil apparatus rises .with

inducspeed to maintain the constancy of current for providing a uniformignition spark at widely varying engine speeds.

In testimony whereof, I have signed my name to this specification this9th day of November 1917.

LIONEL M. WOOLSON.

